Bite wounds & animal bites - ED revision
Bite injuries are common in the emergency department and may appear deceptively minor. Skin can move over deeper structures at the moment of injury, and puncture or crush mechanisms may inoculate polymicrobial flora deep into tissue.
ED management therefore combines a careful risk assessment, appropriate wound care and debridement, considered use of antibiotics, and timely immunisation/rabies/tetanus and safeguarding decisions.
Guideline sources: NICE NG184 (antimicrobials), UKHSA/GOV.UK rabies guidance, and the Green Book (tetanus).
Why bites are high risk
- Direct inoculation of aerobic and anaerobic oral flora into deep tissue, often polymicrobial.
- Puncture and crush mechanisms cause devitalised tissue and reduced antibiotic penetration.
- Certain sites and mechanisms (hands, joints, tendons, clenched‑fist injuries, punctures over bone/cartilage, prosthetic proximity) carry high risk of septic arthritis, tenosynovitis or osteomyelitis.
- Delay to presentation and inadequate irrigation/debridement increase infection risk.
Common pathogens
- Human bites: mixed flora including Streptococcus spp., Staphylococcus aureus, anaerobes and Eikenella corrodens - co‑amoxiclav is preferred for coverage.
- Cat bites: Pasteurella multocida commonly produces rapidly progressive infection from puncture wounds.
- Dog bites: mixed flora including Pasteurella, staphylococci, streptococci and anaerobes; crush injury often causes more tissue loss.
- Special risks: Capnocytophaga canimorsus (dog bites - severe disease in asplenic or immunocompromised patients), unusual zoonoses from wildlife/farm exposures, and blood‑borne virus transmission after human bites (HBV, HCV, HIV).